A magnetic disk device comprises a disk and a magnetic head slider supported by a suspension for writing information into the disk and for reading out information from the disk. The magnetic head slider has magnetic converter elements and slider-flying rails, and the air flow acting on the slider-flying rails causes the magnetic head slider to fly above the disk. A modern magnetic head slider comprises a base portion and an element-forming portion which is joined to the base portion and has the magnetic converter elements formed thereon. Typically, the base portion is made of an altic (AlTiC) material and the element-forming portion is made of alumina.
JP-A-5-28429 discloses a magnetic head slider in which the surface of the element-forming portion is set behind the surface of the base portion so that the gap at the end of the magnetic converter element on the surface of the element-forming portion will not easily come into contact with the disk during use of the slider.
JP-A-7-182628 discloses a magnetic head slider in which a base portion is made of a glass or the like, and the base portion and an element-forming portion are covered with a carbon film.
JP-A-7-230615 discloses a magnetic head slider in which a protection film is formed on only an element-forming portion at a step formed between the base portion and the element-forming portion.
JP-A-2000-173217 discloses a negative pressure type magnetic head slider. A slider-flying rail of the negative pressure type magnetic head slider comprises a first rail portion having a transversal component extending in the transverse direction of the slider body and lengthwise components extending in the lengthwise direction of the slider body from both ends of the transversal component, and two second rail portions arranged at the back of the first rail portion maintaining a gap in the transverse direction of the slider body.
In this magnetic head slider, pneumatic bearings are formed on the surfaces of the first and second rail portions. During use of the slider, a force produced on the surfaces of the pneumatic bearings of the slider-flying rails maintains a balance with a negative pressure produced on the back side of the first floating rail portion in a manner to maintain the flying height which is as small as possible relative to the disk of the magnetic head slider.
A protection film such as a carbon film is formed on the surfaces of the first and second rail portions and on the surfaces of the pneumatic bearings protruding therefrom. However, no protection film has been formed on the surfaces where the slider-flying rail of the slider body protrudes.
There is a tendency to decrease the flying height of the magnetic head slider relative to the disk. The magnetic head slider is brought close to the disk accompanying a decrease in the flying height of the magnetic head slider. A lubricant has been applied onto the surface of the disk and if the magnetic head slider is brought close to the disk, the lubricant on the disk can migrate onto the magnetic head slider as a lublicant vapor or in another form.
There will be no problem if the lubricant migrated onto the magnetic head slider from the disk is washed and removed from the magnetic head slider. However, if the lubricant deposits on the magnetic head slider, there arises a problem that the magnetic head slider loses balance to adversely affect the magnetic converter elements. If there is a step formed between the element-forming portion made of alumina and the base portion made of the altic material, the lubricant can easily deposit on the stepped portion. In the production thereof, a surface of the magnetic head slider is flattened by machining such as lapping. However, as the hardness is not the same between the element-forming portion and the base portion, a very small step can be formed between the element-forming portion and the base portion. As a result, when the lubricant adheres near the magnetic converter elements, it can adversely affect the magnetic converter elements, or can cause stiction of the flying slider during the “seeking” operation of the disk, thereby, deteriorating the flying profile of the head and impairing the stability in the characteristics.